I am considering the Time-sert but there are numerous choices - do I need the extended version? Anyone recommend a kit for my application?

I'm not sure it's worth the cost as I've read a lot of "good" Helicoil stories...but I also own a 560SL with the same spark plug size, so it might be worth the investment.

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE